A Primer on Tommy John Surgery: Part One

Tommy John surgery (TJS) interest was all the rage earlier this season, when everyone’s favorite pitcher, Stephen StrasburgMatt HarveyJose Fernandez, found out that he needed the surgery. Besides Fernandez, 51 other pitchers have needed to go under the knife for the same procedure this year alone. Since Fernandez was lost for the season, quite a bit of additional research has become available to help fill in some of the blanks.

Today and tomorrow, what I have attempted to do is compile as much of the current knowledge about Tommy John surgeries in the major leagues as I could, with the hope that bringing it together can help us build our knowledge base. In doing so, I have identified a number of areas for further research, and I will interject these in italicized paragraphs labeled “Help Out” during the course of these two articles, as well.

We’ll cover much of the same ground in these two articles as, again, my goal is to compile as much information as possible, and these articles had some very valuable information within them. I will also be adding my own and other information as well. I have put in all the known information I have found useful on major league Tommy John surgeries. As additional information becomes available, I plan to go back and update these articles with the missed or new data. Basically, I envision these articles to be one-stop shopping for years to come on known facts for the surgery at the major league level.

Before looking at the state of research on TJS, we need to start with The List. Baseball research was in its infancy until Retrosheet was freely available to everyone. Looking at Tommy John surgeries was impossible until people knew who had had the operation. A list had to be created. Back in 2011, I asked the community’s help in creating a list and got enough players to at least get a starting point.

Then came Jon Roegele. He combined my list with one of his own and also gathered input from others to create a list of 448 players who had undergone Tommy John surgery. As of today, the list stands at 737 players, and Jon adds players as soon as he finds out about them. A big thanks needs to be given to Mr. Roegele, as just about none of the following work could have been done without his efforts.

The research and debate on the subject has increased as the number of MLB pitchers who have needed the operation has exploded over the past couple of seasons. This graph illustrates the changes on a year-by-year basis:

Help Out: Provide the MLBIDs or Retrosheet IDs for the all the players on The List. While not useful to everyone, for those with database knowledge, it would speed up their research many times over. Done, thanks to Mr Roegele for knocking it out (afternoon of 6/30/14).

With the list complete, some useful information can be obtained. Today, I will focus on how a player’s production is affected by the surgery, as well as how long it takes to return from the surgery.

As an aside, allow me to apologize in advance if I have missed anybody’s research. Quite a bit has become available recently, and it is a challenge to keep up with it all. Please let me know in the comments and I will add the information to the article.

Effects of Tommy John Surgery on Performance

When looking at how pitchers performed before and after the surgery, I am going to go with information I know and trust because I worked on it. In the The Hardball Times Annual 2013, Brian Cartwright and I looked at the effects of returning from Tommy John surgery.

Starting with velocity, we looked at four seasons.

Season 1: Last full healthy season

Season 2: Season of TJS

Season 3: Season of return from TJS

Season 4: First full season after TJS

With this set-up, a healthy baseline is set before and after the operation. Also of note, not all pitchers are compared in each group. If a pitcher had Tommy John surgery in spring training, there would be no data to compare for the “Season of TJS.” Additionally, we used both weighted (by total pitches) and unweighted samples because pitch speed stabilizes quickly.

Season: Weighted, Non-weighted

Season 1 to 2: -0.10, -0.37

Season 1 to 3: +0.14, +0.05

Season 1 to 4: -0.07, -0.80

Besides our article, The American Journal of Sports Medicine looked at velocity decline and found similar values.

Time Frame: Decline

1 year before surgery to 1 year after: -0.2 mph

1 year before surgery to 2 years after: -0.1 mph

Up to 3 years before surgery to up to 3 years after: -0.4 mph

With the preceding information, a couple of points can be made.

Tommy John surgery doesn’t help a pitcher increase velocity. While there was a small increase from Season 1 to Season 3 in our sample, it would not be worth it for a pitcher to miss at a minimum one season to see a 0.1 mph bump that they then will immediately lose. Probably most of the increase is from a decline in production before the injury knocked them out of action, as well as the time spent rehabbing.

While TJS doesn’t increase velocity, it does seem to limit the effects of aging. On average, a pitcher with lose 0.25 mph on his fastball per season. With the time off for the surgery, some need rest and a regimented workout plan, as Tommy John recipients come back not aging as much. Here is an aging curve graph for all pitchers and those who had the surgery.

After surgery, pitchers don’t see a huge jump in velocity. So how did they perform coming back? I will use the same two studies to tackle this question.

In the Hardball Times study, we looked at the “percentage difference between their pre-surgery projected performance and their actual performance.”

Rate Statistics Following Tommy John Surgery As Compared to Projected Performance Before Surgery

Season after returning

ERA

HR/9

BB/9

K/9

One

5.80%

7.20%

5.00%

-4.40%

Two

0.60%

-2.00%

0.70%

-1.60%

Three

0.20%

2.10%

0.70%

-0.90%

Here are the values from AJSM:

AJSM Findings – 1 year before surgery to 1 year after

Season

ERA

K/BB

K/9

1 year before surgery

4.33

2.33

7.5

1 year after surgery

4.60

2.27

7.3

AJSM Findings – 1 year before surgery to 2 years after

Season

ERA

K/BB

K/9

1 year before surgery

4.16

2.4

7.7

2 years after surgery

4.46

2.2

7.3

AJSM Findings – Up to 3 years before surgery to up to 3 years after

Season

ERA

K/BB

K/9

Up to 3 years before surgery

4.23

2.34

7.5

Up to 3 years after surgery

4.63

2.29

7.3

The first season back from Tommy John is by far the worst for the pitcher, with all major stats headed in the wrong direction. By the second year, most stats have stabilized, except strikeouts. It’s not surprising to see strikeouts decline, since velocity is also declining.

Return Times and Success Rates

The rehabilitation rate for successful Tommy John surgeries has been exacted down to a science. Will Carroll found that first-time TJS recipients could expect to be back in the majors between 12 and 18 months after going under the knife, but recently even that has adjusted downward:

The recovery is very predictable, ranging from nine to 12 months, down from the original 12 to 18 months. We still see setbacks during the rehab process, though outright failures of the sort Daniel Hudson from the Diamondbacks had, necessitating a redo of the procedure this summer, are very rare.

Help Out: Pitchers perform worse in the season they return to the majors. One potential study could be to break this down by the specific number of months it takes the pitcher to return–12 months, 13 months, etc. Or more encompassing, how the pitcher performs in X months after the surgery. Perhaps the loss in production happens in the first few months, but after 15 months, pitchers are then at 100 percent.

The success rate for the surgery is getting better, but is still not perfect. We can look at the AJSM for a couple of studies on Tommy John surgery success. The first study looked at 26 years worth of data, from 1986-2012:

The study also showed that 83 percent of the pitchers they looked at made it back to the majors after surgery and 97 percent were at least able to pitch in a minor-league game after the surgery.

The second study by the AJSM looked at 147 cases from 1999 and 2011. They found a small increase in the success rate.

Among the players [147], 29 (20%) failed to return to MLB competition, 19 (13%) returned only to active status (failing to appear in >= 10 games in a single season), and the remaining 99 (67%) returned to established play after surgery.

One study puts the number at 83 percent and the other 80 percent. Basically, one out of every five pitchers who have the surgery just aren’t able to make it back (seeChad Billingsley).

The newest cool trend is a second Tommy John surgery. This area is ripe for some research. In the 2013 THT Annual, we found pitchers had about 650 innings between their first and second procedure, though the sample size was miniscule. Recently, I ran a brief study using the up-to-date TJS database and found those pitchers who had their first TJS from before 2011 averaged 4.5 years until they needed to go under the knife again, with a median time of 4.0 years. These numbers are in the ballpark of the 650 innings value we originally found.

Help Out. A lot can be done here. First, what is the average return time for pitchers with the second surgery? What is the success rate for all of them? How do these pitchers (velocity and stats) compare to before and after? What percentage of productive first TJS recipients need a second surgery?

Tomorrow, I will examine the possible causes that lead one to need Tommy John surgery, talk about the kinds of prevention available, and also detail my conclusions as to where we stand right now.

About Jeff Zimmerman

Jeff writes for FanGraphs, The Hardball Times and Royals Review, as well as his own website, Baseball Heat Maps with his brother Darrell. In tandem with Bill Petti, he won the 2013 SABR Analytics Research Award for Contemporary Analysis. Follow him on Twitter @jeffwzimmerman.

Comments

Interesting article.
I have a question. I have not really seen much written about stem cells and their effect if used in season. Do players have an option to receive stem cells during the season? Is there a recovery time associated with the process?
I dont think that TJS and stem cells are related, but stem cells can definitely repair injuries and strains that may lead to adjusted mechanics and TJS.

You probably haven’t seen much written about stem cells because stem cell-based treatments aren’t FDA approved. The risks are high, and there is uncertainty about their effectiveness. While there may be some therapeutic use of stem cells illegally within the US or outside the US where regulations are not as strict, there isn’t any data so there’s no way to study it.